The position of a mobile device is useful for a variety of applications including navigation, routing and mapping applications. While the location of mobile devices that are outside can be determined utilizing a Global Positioning System (GPS) or other conventional techniques, the location of a mobile device that is indoors must sometimes be determined in a different manner. For example, mobile devices that are in large buildings or buildings that are constructed or otherwise secured in a manner that limits cellular communication by the mobile device may not be located or at least may not be located in an accurate manner by GPS or other conventional techniques. As such, a number of techniques have been developed in order to determine the position of mobile devices in an instance in which the mobile devices are indoors. These indoor positioning techniques do not rely upon cellular communication and, instead, generally utilize various other wireless network technologies.
For example, mobile devices may be configured to wirelessly broadcast identification information to receiving units, such as scanners, located at predefined positions. The receiving units, such as the scanners, include smart antennas, such as phased array antennas or multiple directive receiving antennas, for determining the angle of arrival of the signals broadcast by the mobile devices in order to identify the position of the mobile devices. Alternatively, the indoor position of a mobile device may also be determined utilizing a radio frequency (RF) fingerprint technique or a received signal strength (RSS) scene analysis. These localization techniques estimate the position of the mobile device by matching radio signals, e.g. fingerprints, provided by other devices or objects in proximity to the mobile device to a radio map. In order to support these localization techniques, radio mapping is initially performed prior to utilizing the resulting radio map for positioning of the mobile device. During the radio mapping, the position coordinates and RSS of radio signals, e.g., fingerprints, provided by devices and objects are gathered. In order to determine the position of the mobile device, the radio signals received by the mobile device are compared to the fingerprints that were identified during construction of the radio map and the position the mobile device is estimated based upon the closest match therebetween.
The indoor positioning of a mobile device may also be determined by triangulation. One example of triangulation is angulation, also known as angle of arrival or direction of arrival. An angulation technique estimates the location of a mobile device based upon the angle of the mobile device to various reference points. Another technique for determining the indoor position of a mobile device utilizes time of arrival. In this regard, the distance between two devices is measured utilizing the one-way propagation time for signals transmitted between the devices which, in turn, is dependent upon a predefined signal propagation speed. Alternatively, the indoor position of a mobile device may be determined by utilizing proximity that provides symbolic relative localization information. For example, if a mobile device is detected by a single reference unit, the location of the mobile device is associated with a location of the single reference unit. However, in an instance in which a mobile device is detected by multiple reference units, the location of the mobile device may be related to the position of the reference unit that communicates with a mobile device with the strongest signal.